OBJECTIVETo assess the efficacy and safety of drainage for the control of the complications following impacted mandibular third molar extraction.

METHODSTo retrieve randomized controlled trials assessing the efficacy and safety of drainage for the control of the complications following impacted mandibular third molar extraction, bibliographic databases including MEDLINE, Cochrane Controlled Trials Register, EMBASE, OPEN SIGLE and China Biology Medicine Database (CBM) were searched on August 23th 2011. References of the included studies and Chinese dental journals were hand-searched. The risk of bias were used by Cochrane Collaboration's tool and the data were extracted. Meta-analysis was done with Revman 5.1.

RESULTSNine articles met the eligibility criteria and were included, seven randomized controlled trials and 2 quasi-randomized controlled trials. Seven of these studies had unclear risk of bias and 2 had high risk of bias. Drainage could significantly increase 4.44 mm of the post-operative maximal mouth opening (P = 0.003), relief facial swelling (P < 0.05) and reduce post-operative complications (P = 0.008). But no evidence showed that drainage had a positive effects on post-operative pain (P = 0.09).

CONCLUSIONDrainage could probably control the complications following impacted mandibular third molar extraction; but more randomized controlled trials are needed to reinforce the conclusion.